Directional inclinometer

ABSTRACT

A device for indicating and recording data representative of direction and degree of inclination of a body or a line or of current direction and velocity by means of a tethered buoyant pendulum is provided. The device includes an outer sphere, one half of which is lined with concentric circles of various colors, and an inner hemispherical chassis which is adapted to float within the outer sphere on a thin layer of liquid between the spheres. The chassis carries photographic equipment and magnets, the former photographing arcs of the concentric circles to indicate current velocity and the latter aligning the chassis so that inclination and direction are indicated by the colors and positions of the arcs photographed.

United States Patent Stimson 51 Dec. 19, 1972 [54] DIRECTIONALINCLINOMETER [72] Inventor: Paul B. Stimson, Falmouth, Mass.

[73] Assignee: The United States of America as represented by theSecretary of the Navy [22] Filed: Oct. 22, 1970 [21] Appl. No.: 82,884

[52] US. Cl. ..73/189, 33/2055 P, 33/206 CB [51] Int. Cl. ..G0lp 5/00[58] Field of Search ..73/l70 A, 189; 33/2055 P,

[5 6] References Cited UNITED STATES PATENTS Erdely ..73/l89 Donaldson..33/206 CB Primary Examiner-Jerry W. Myracle Attorney-R. S. Sciascia,L. I. Shrago and C. E. Vautrain, Jr.

[5 7 ABSTRACT A device for indicating and recording data representativeof direction and degree of inclination of a body or a line or of currentdirection and velocity by means of a tethered buoyant pendulum isprovided. The device includes an outer sphere, one half of which islined with concentric circles of various colors, and an innerhemispherical chassis which is adapted to float within the outer sphereon a thin layer of liquid between the spheres. The chassis carriesphotographic equipment and magnets, the former photographing arcs of theconcentric circles to indicate current velocity and the latter aligningthe chassis so that inclination and direction are indicated by thecolors and positions of the arcs photographed.

\ marina-Il e? PATENTEB Mr: 1 9 m2 SHEET 1 OF 2 lNVE/VTOI? Paul B.timson BY [ff PRO- GRAMMER PATENTED 19 I97? 3. 706. 225

sum 2 or 2 INVENTOR Paul B. Stimson DIRECTIONAL INCLINOMETER Theinvention described herein may be manufactured and used by or for theGovernment of the United States of America for governmental purposeswithout the payment of any royalties thereon or therefor.

This invention relates to inclinometers and, more particularly, to afreely movable chassis and means associated therewith for automaticallymeasuring and recording in situ a multiplicity of positions assumed bythe body in which the chassis is mounted.

Many directional inclinometers are available for measuring in variousways parameters relating to motion, attitude and direction and,particularly in the oceanographic field, for measuring and indicatingwave and current parameters. These prior devices, however, are eithertoo complex or too costly, or both, to be used in large numbers or incircumstances where they may be disposed without appreciable loss ofafter use. The present invention provides a simplified directionalinclinometer which avoids the disadvantages of prior devices, is capableof storing on the order of 10 to units of information and is applicablein all situations where inclinometers are used, among other attributes.

The directional inclinometer of the present invention may be affixed toa buoy or float to detect and record pitch and roll or attached in amooring cable to indicate inclination or used in any of manyapplications where direction, motion and attitude are desired to besensed either collectively or individually. For conciseness, thedescription contained herein will be directed to a current meterembodiment only.

The present invention includes a hollow sphere which may be affixed to abuoy or other buoyant object or tethered to a fixed point, such as afitting on a mooring cable or to a bottom weight, among otherapplications. The sphere contains a free-floating hemisphere whichcomprises a chassis carrying a camera and associated equipment, magnetsfor maintaining the chassis in line with the earths magnetic field andballast weights to align the camera with the zenith. The interior of theupper half of the sphere has inscribed therein a plurality of concentriclines of different color at selected spaced intervals. Lights on thechassis illuminate the zenith above the camera at any inclined positionof the sphere so that the frames will show an indication of inclinationby the colors and positions of the lines appearing therein. A highrecording density is obtained by photographing the lines through amatrix of discrete holes, film advance between exposures being thediameter of a hole. The high density is unaffected by rotation of theouter sphere about the chassis.

Accordingly, it is an object of the present invention to provide aninclinometer that is simple in operation, inexpensive to manufacture andreliable at any selected depth.

Another object of this invention is to provide an inclinometer employingthe pendulum or inverse pendulum principle which may record on the orderof 10" to 10 measurements of current velocity and direction during asingle use.

It is a further object of this invention to provide an inclinometerhaving a high recording density which is unaffected by rotation of itspolar axis.

Other objects, advantages and novel features of the invention willbecome apparent from the following detailed description thereof whenconsidered in connumerals represent like parts throughout and wherein:

FIG. 1 is a sectional view of a preferred embodiment of the inventionwith operative components indicated schematically;

FIG. 2 is a bottom view of the matrix of FIG. 1;

FIG. 3 is a schematic diagram of the embodiment of FIG. 1 at a selectedattitude in a water environment;

FIG. 4 is a bottom view of the matrix at the attitude in FIG. 3;

FIG. 5 is a schematic diagram of the embodiment of FIG. 1 at a differentattitude from that in FIG. 3;

FIG. 6 is a bottom view of the matrix at the attitude in FIG. 5;

FIG. 7 is a schematic diagram of the embodiment of FIG. 1 at a differentattitude; and

FIG. 8 is a bottom view of the matrix at the attitude in FIG. 7.

Referring to FIG. 1, there is shown a particular embodiment of thecurrent meter as indicated at 11, in-

I cluding an outer glass sphere 12 formed of two halves indicated at 26,the strength of the magnets being determined by the torque desired inmaintaining chassis 16 aligned with the earths magnetic field. Camera18, programmer 19 and light sources 24 and 25 are connected byconventional means to the batteries so that the device may operateautomatically. Programmer 19 contains a timer and related electrical andmechanical components, not shown, for operating camera 18 and lights 24and 25 at selected intervals of time. Camera 18 is centrally positionedwithin hemispherical chassis 16 and has its lens 30 centrally disposedon the chassis. A preferably square matrix 31 preferably is positionedprecisely in a focal plane of lens 30 so that the view of the camera isalways directed through the matrix towards the zenith of sphere 12 whichis determined by the position of chassis 16 therein.

Matrix 31 may be positioned as close as possible to the inner surface ofsphere 12 as shown, and miniature lights, not shown, may be attachedthereto to illuminate the adjacent area of the sphere. The matrixprobably would be most effective if it could be placed directly on thesurface of the camera film as indicated at 32. Sphere 12 has secured toit at its outer surface a tether 35 which may be attached at one end tothe sphere by a bolt 35 and a locking nut 37. The tether is secured atits other end to a mooring or other device by conventional means, notshown.

In FIG. 1, sphere 12 is shown positioned in a body of water 40 in whichthe direction of current is indicated by arrows 41. Sphere 12 has a polemarked opposite the point of attachment of tether 35, as indicated at42, so that when tethered in current 41 the drag on the sphere willcause the sphere to be displaced at the angle tether 35 makes with thenormal and also will cause chassis 16 to assume a position the zenith ofwhich is at the same angle from pole 42. Sphere 12 has drawn on itsinner surface a plurality of lines 44 which are each of a differentcolor or of an arrangement of different colors. Lines 44 could also beformed of characters such as dots, circles, arrowheads, squares, dashes,etc., in addition to or exclusive of the use of colors. Each linerepresents a current velocity as determined by the drag coefficient ofthe attitude assumed by the sphere. At angle A, shown in FIG. 1, camera18 will photograph lines 44 which appear within a selected distance ofthe zenith, this selected distance being illuminated by light sources 24and 25 and indicated at 46.

FIG. 2 is a plan view of matrix 31 at the attitude shown in FIG. 1 andincludes portions of lines 44 which appear at the zenith of the sphereand which are seen through small openings in the matrix as indicated at47 and 48. Matrix 31 is shown skewed to the axis of film advance whichis indicated at 45.

FIGS. 3, 5, 7 and 9 show sphere 13 is various attitudes with respect tosphere 12. FIGS. 4, 6, 8 and are bottom views of matrix 31 at theattitudes assumed by chassis 16 in FIGS. 3, 5, 7 and 9, respectively.

In a preferred embodiment of the invention, chassis 16 is an opaqueplastic hemisphere having an outside diameter only slightly less thanthe inside diameter of a 9 VI-inch glass sphere 12. Plastic chassis 16floats on the thin liquid film 17 and is ballasted in a manner, notshown, to maintain its equator in a horizontal attitude. Sufficientpermanent magnets 26 are installed to maintain chassis 16 oriented withrespect to magnetic north regardless of the attitude of outer sphere 12.The spacing of circles 44 is selected with respect to the field of viewof camera 18 so that a segment of at least one circle or the polar dotis always in view. The color, position and orientation of a line orlines across the field of view thus uniquely define the attitude ofsphere 12 except for rotation about its polar axis, which rotation isimmaterial and does not affect the sensitivity of the system.

The present invention provides the sensitivity required above by beingcapable of recording exposures at a spacing apart equal to the diameterof a matrix opening such as the holes shown. The skewing of thelongitudinal axis of matrix 31 with respect to the direction of filmadvance is essential to this high density of recording. When thedeveloped film is projected through a similar matrix, only one exposureat a time will be projected. Film advance along axis 45 could be relatedto the sprocket holes in the film in lieu of to frame spacing in amanner not shown.

In FIG. 3, sphere 12 is in a stronger current and in a differentmagnetic field than shown in FIG. 1, the current direction beingessentially eastward. Lines 44 appear through matrix openings 50 53,inclusive. In FIG. 5, the magnetic field is the same as in FIG. 3, butthe current is less so that polar circles nearer the pole of sphere 12are photographed, permitting lines 44 to appear through matrix openings54 56, inclusive, as shown in FIG. 6. FIG. 8 shows the matrix view ofsphere 12 in FIG. 7, indicating a southward current and also that lines44 appear in openings indicated at 62 through 66. In operation, aparticular angle of tether 35 and a particular magnetic field such asthose indicated in FIGS. 2, 3, 5 and 7 will cause corresponding sectors46 to appear at the zenith of sphere 12. In any set of conditions oftether angle and magnetic field, film advance is preferably a distanceof one hole diameter per exposure.

The present invention thus provides for a very great quantity ofinformation on current strength and direction to be recorded in acompact and inexpensive device. The device is insensitive to rotation ofsphere 12 about the tether as an axis, which feature makes possible thehigh recording density and also enhances reading of the records bymachines. The use of matrix 31 also facilitates the very short filmadvance between exposures which, among other things, sorts out themultiplicity of data that ordinarily would appear and would confuse andmake more difficult data reductions.

By means of the present invention, a large number of relativelyinexpensive currentrneters may be deployed in several contiguous areasvia asingle vessel and mission. The meters may be placed in any depthand may be recovered either by capture or by timedrelease via solublediscs or other conventional means for effecting remote release ofsubmerged objects. Minor inaccuracies occurring through changes in thecenter of gravity of chassis 16 may be compensated for by introducing anequal and opposite motion or may be allowed for in the data reductionprocess.

Obviously many modifications and variations of the present invention arepossible in the light of the above teachings. For example, the cameralens may be dispensed with and a bundle of optical fibers substitutedwhich would extend substantially to the inner surface of sphere 12 toconduct information to the camera film. Also, the outer glass sphere maybe made opaque for use in the euphotic zone.

What is claimed is:

l. A current meter adapted to detect and record a multiplicity ofcurrent velocity and direction indications comprising:

a hollow sphere having means for exterior attachment to a tether at onepole and a plurality of individually distinguishable concentric lines onits interior surface about the opposite pole, said lines extending atleast to the equator between said poles;

a tether attached at one end to said sphere and at the other end to amooring or a bottom weight;

a small amount of liquid in said sphere and a hollow chassis meanssubstantially hemispherical in shape disposed in said sphere and adaptedto float on a thin film of said liquid; said chassis having meansmounted therein for aligning it with the environmental magnetic field;

a camera and lighting means for use therewith mounted on the planarsurface of said chassis, said camera and said lighting means positionedon said chassis and directed so that a limited area of said sphere atthe zenith of said chassis will be illuminated and photographed; and

control and power means for operating said camera and energizing saidlighting means, whereby drag of said sphere in a current causesinclination of said tether and said sphere, said chassis assuming ahorizontal attitude and said camera photographing portions of theconcentric lines indicating current velocity.

S 6 2. The device as defined in claim 1 wherein said conformation on theorder of 10 to current centric lines are distinguishable from oneanother by readings in one sampling. c0101 alone- 4. The device asdefined in claim 3 wherein the lens devic? as Ffi in claim 2 and furtherof the camera and the matrix are replaced by a plurality eluding amatrix positioned between the camera and 5 f p i lfib the zenith forlimiting the portions of said concentric said fibers having their outerends disposed near the lines which are viewed by said camera,

said matrix being substantially square, said transverse axis skewed tothe direction of film travel to facilitate the recording of a density ofininner surface of said hollow sphere to receive a more distinct imageto conduct to said camera.

1. A current meter adapted to detect and record a multiplicity ofcurrent velocity and direction indications comprising: a hollow spherehaving means for exterior attachment to a tether at one pole and aplurality of individually distinguishable concentric lines on itsinterior surface about the opposite pole, said lines extending at leastto the equator between said poles; a tether attached at one end to saidsphere and at the other end to a mooring or a bottom weight; a smallamount of liquid in said sphere and a hollow chassis means substantiallyhemispherical in shape disposed in said sphere and adapted to float on athin film of said liquid; said chassis having means mounted therein foraligning it with the environmental magnetic field; a camera and lightingmeans for use therewith mounted on the planar surface of said chassis,said camera and said lighting means positioned on said chassis anddirected so that a limited area of said sphere at the zenith of saidchassis will be illuminated and photographed; and control and powermeans for operating said camera and energizing said lighting means,whereby drag of said sphere in a current causes inclination of saidtether and said sphere, said chassis assuming a horizontal attitude andsaid camera photographing portions of the concentric lines indicatingcurrent velocity.
 2. The device as defined in claim 1 wherein saidconcentric lines are distinguishable from one another by color alone. 3.The device as defined in claim 2 and further including a matrixpositioned between the camera and the zenith for limiting the portionsof said concentric lines which are viewed by said camera, said matrixbeing substantially square, said transverse axis skewed to the directionof film travel to facilitate the recording of a density of informationon the order of 105 to 106 current readings in one sampling.
 4. Thedevice as defined in claim 3 wherein the lens of the camera and thematrix are replaced by a plurality of optical fibers, said fibers havingtheir outer ends disposed near the inner surface of said hollow sphereto receive a more distinct image to conduct to said camera.